Re: [SKOS] semantics

[+cc Sandro Hawke]

Hi Alistair,

(obviously, with my Activity Chair's hat on:-) I wonder whether, at some
point, it would not be valuable to talk with the RIF guys. Indeed, it
*may* (emphasize on the conditional:-) be possible that the semantic
conditions could be expressed in what the RIF people call the 'core'.
And if it is not, then it is an interesting data point for them!

Obviously, I would like to reduce the number of specification-dependent
implementation requirements. Ie, it would be nice if a system is
RDFS+RIF Core aware (which may be a viable configuration at some point)
then this woulc automatically be SKOS aware, by feeding in the right
RDFS and RIF definitions. There might be two issues stading in the way,
though (without having made a thorough analysis, not being a logician
either): I am not sure whether the RIF core could express the transitive
closure of a predicate easily; and whether the datatype mapping they use
has any regard for the language tags...

I am happy to put this issue to the Coordination Group's agenda at some
point *if* you feel it would be helpful

Ivan

Miles, AJ (Alistair) wrote:
> Hi all,
> 
> There are two basic challenges with respect to the semantics of SKOS.
> 
> Firstly, what are the semantics of SKOS?
> 
> Secondly, how should the semantics of SKOS be specified?
> 
> Niether question is trivial.
> 
> The difficulty with the first question is that, while there are some semantic conditions which are intuitively obvious (such as skos:broader and skos:narrower being each other's inverse), there are others which are not at all obvious and for which there may be viable alternatives (such as reflexivity of skos:broader).
> 
> The difficulty with the second question is that, even if we only consider those semantic conditions which are not contentious, not all of those conditions may be specified by means of either RDFS or OWL assertions.
> 
> One *possible* way forward would be to define the semantics of SKOS as a semantic extension of RDFS, using the definitions and notational conventions laid out in the RDF Semantics [1].
> 
> To explore the feasibility of this approach, and to provide a concrete basis for discussion of specific semantic conditions, I have written a draft semantics of SKOS as a semantic extension of RDFS:
> 
> [2] http://www.w3.org/2006/07/SWD/wiki/SkosDesign/RdfsSemanticExtension?action=recall&rev=6
> 
> Note that this draft only considers a limited subset of the current SKOS vocabulary - but don't worry, there is still plenty of potential for debate :)
> 
> [DONE] ACTION: Alistair to summarizes the aspects of semantics of the skos data model [recorded in http://www.w3.org/2007/01/22-swd-minutes.html#action06]
> 
> Cheers,
> 
> Alistair.
> 
> [1] http://www.w3.org/TR/2004/REC-rdf-mt-20040210/
> 
> --
> Alistair Miles
> Research Associate
> CCLRC - Rutherford Appleton Laboratory
> Building R1 Room 1.60
> Fermi Avenue
> Chilton
> Didcot
> Oxfordshire OX11 0QX
> United Kingdom
> Web: http://purl.org/net/aliman
> Email: a.j.miles@rl.ac.uk
> Tel: +44 (0)1235 445440
> 
> 
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
URL: http://www.w3.org/People/Ivan/
PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html
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